The present invention relates to an iris recognition system as one of the personal identification systems and particularly to an iris pickup apparatus using a wide-angle and a telephotograph camera for obtaining an iris image.
There is a known system of making personal identification by the use of an iris pattern as one of the personal identification systems for security. Unlike fingerprints, the iris recognition has the advantage that it is only needed to pick up an iris image with a separated camera in non-contact condition and that the misidentification percentage is extremely low but the recognition accuracy is high, so that the spread of the iris recognition is greatly expected in future. On the other hand, the use of such an iris image is restricted by the fact that the iris image has to be clear and picked up quickly during the time an object of recognition is at a standstill.
As an iris pickup system meeting the above restrictions, there is a known iris pickup apparatus using two kinds of cameras including a wide-angle camera and a narrow-angle camera as described in Japanese Patent Publication No. 2000-23946, for example.
The iris pickup apparatus is so arranged as to operate through the steps of recognizing a face image by pattern matching out of images of persons as photographic objects picked up by the wide-angle camera, determining the position of the right or left eye from the face image, directing the narrow-angle camera as a telephotograph camera toward the iris and accurately focusing the lens of the camera on the iris by the use of the autofocusing technique.
The above iris pickup apparatus will now be specifically described by reference to the drawings.
FIG. 9 is an external perspective view of the cameral unit of a conventional iris recognition apparatus. The camera unit has a wide-angle camera 101, a telephotograph camera 102, a mirror 103 for directing an optical axis to the front as the telephotograph camera 102 is turned sideways, a panning motor 104 for panning the mirror 103, a link 105 for transmitting the torque of the panning motor 104, a tilt table 106 for holding the link 105, a tilt motor 107 for turning the tilt table 106, and a support tables 108 for holding the tilt table 106 and the tilt motor 107.
In the iris pickup apparatus having the camera unit thus arranged, the face of a person is picked up by pivotally tilting the tilt table 106 by means of the tilt motor 107 so that the whole person""s face as a photographic object is picked up by the wide-angle camera 101. Then the position of the right or left eye of the person""s face is determined from the image thus picked up. Further, the tilt table 106 is pivotally tilting so as to set the optical axis of the telephotograph camera 102 to the eye position thus determined and the mirror 103 is pivotally panned by the panning motor 104. When the eye position is reached, an iris image is picked up by focusing the lens of the camera on the iris by the use of the autofocusing technique.
However, since the wide-angle camera 101 and the telephotograph camera 102 are disposed horizontally along the tilt pivot shaft in the above iris pickup apparatus, the optical axes of the cameras fails to coincide with each other and this causes a parallax between the cameras to occur. Consequently, it has been needed to adjust the direction of each camera so that the optical axes of the wide-angle camera 101 and the telephotograph camera 102 cross each other to provide the same imaging position after various parts are assembled.
It is therefore an object of the invention made in view of the above situation to provide an iris pickup apparatus easy to operate without requiring troublesome adjustment of the directions of a wide-angle camera and a telephotograph camera.
Firstly, an iris pickup apparatus according to the invention comprises a first camera for picking up the image of a photographic object, a second camera for picking up the iris of the photographic object, a panning mechanism for panning the second camera, and a tilt mechanism for pivotally tilting the first camera and the second camera, wherein
the tilt mechanism is so arranged as to pivotally tilt the first camera and the second camera on the same plane as the optical axis planes of these cameras.
Thus, the optical axis of the first camera and the optical axis of the second camera are caused to coincide with each other when an image is picked up thereby.
Secondly, the tilt mechanism includes a tilt stand for holding the first camera, the second camera and a panning motor, a tilt motor for pivotally tilting the tilt stand, and support tables for holding the tilt stand and the tilt motor.
Thus, the first camera and the second camera both can be made to perform a tilt operation.
Thirdly, the panning mechanism is so arranged as to pivot the first camera and the second camera on a panning shaft perpendicular to a tilt shaft for pivotally tilting the first camera and the second camera.
Fourthly, cleaning brushes for cleaning the lenses of the respective first and second cameras are preferably provided on the pivotal orbits of these lenses when the first camera and the second camera are pivotally tilted.
As the cleaning of the lens of each camera can be done simultaneously with the iris recognizing operation, the lenses are always kept clean. Moreover, a clear image without blurs and dust trances becomes available, whereby lens maintenance work need not be done very often.